Machine-made sand anti-segregation concrete and preparation method thereof

Abstract

The present invention belongs to the technical field of building materials, and the present invention relates to a kind of machine-made sand anti-segregation concrete, and more specifically to a polycarboxylate water reducer (JHN-WR001) for machine-made sand anti-segregation concrete. The present invention is based on the molecular design modification of the polycarboxylate water reducer to achieve the integrated functions of high water reduction, high collapse retention and high thickening of the polycarboxylate water reducer. The key points of the design are to use (2,7-octadiene-1-yl) succinic anhydride and polypropylene glycol monobutyl ether to obtain an ester monomer, which is then polymerized by methacrylic acid monomer and methallyl polyoxyethylene ether.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and the invention relates to a machine-made sand anti-segregation concrete, and more specifically to a water reducing agent for the machine-made sand anti-segregation concrete. Background Art

[0002] In the context of environmental protection and green development, the application of machine-made sand concrete in civil engineering has received increasing attention. However, the high segregation rate or large slump loss of machine-made sand concrete seriously affects the strength and durability of concrete, which seriously restricts the widespread application of this type of green concrete. In order to improve the anti-segregation performance of machine-made sand concrete, in-depth basic theory and key technology research has been carried out at home and abroad. The main research work can be summarized into the following three aspects:

[0003] (1) By reducing the water-powder volume ratio of machine-made sand concrete, the slump expansion, passability and self-compactness of concrete are improved, and the segregation rate is reduced.

[0004] (2) By adding concrete viscosity enhancer (VMA) or nanoclay, the plastic viscosity and yield stress of the slurry can be improved to prevent bleeding and segregation.

[0005] (3) By adding mineral admixtures with high specific surface area such as nano-silicon dioxide and silica fume, the rheological properties of concrete can be controlled and the workability of concrete can be improved.

[0006] (4) The use of a single anti-segregation agent in combination with a polycarboxylate water-reducing agent (Concrete, 2018, 9, Performance Study of Anti-Segregation Agents Special for Polycarboxylate Water-Reducing Agents) solves the problems of concrete seepage, bottom grabbing, and compaction caused by polycarboxylate water-reducing agents.

[0007] The above technical approach can effectively overcome the segregation of machine-made sand concrete. However, increasing the water-powder volume ratio requires increasing the amount of cementitious materials, which runs counter to the concept of green development; adding thickeners, nanoclays, nanosilica, silica fume, or using anti-segregation agents alone in combination with polycarboxylic acid water reducers will increase the cost of concrete manufacturing. Summary of the invention

[0008] The present invention solves the problem of high segregation rate of machine-made sand concrete. By integrating water-reducing agent application technology and based on the molecular design and modification of polycarboxylic acid water-reducing agent, the integrated functions of high water reduction, high slump retention and high thickening of polycarboxylic acid water-reducing agent are realized. The applicant has developed a special water-reducing agent JHN-WR001 for machine-made sand concrete, which can achieve the above excellent performance and has realized pilot production.

[0009] According to the first aspect of the present invention, the present invention provides a polycarboxylate water reducer (JHN-WR001) for machine-made sand concrete, which is prepared by the following method:

[0010] (1) mixing polypropylene glycol monobutyl ether, unsaturated acid anhydride, sulfuric acid and a polymerization inhibitor, heating to carry out a solvent-free reaction to obtain an esterification monomer, cooling to room temperature and diluting with purified water to obtain a first mixed solution;

[0011] (2) adding methyl allyl polyoxyethylene ether to the first mixed solution, mixing, heating, and stirring to dissolve to obtain a second mixed solution;

[0012] (3) Mixing methacrylic acid monomer and deionized water to obtain a monomer solution; mixing a reducing agent, a chain transfer agent and deionized water to obtain a functional additive solution;

[0013] (4) The second mixed solution is heated to 65-70°C, an initiator is added, and the mixture is kept warm for 15-30 minutes. Then, the methacrylic acid monomer solution and the functional additive solution are added dropwise at the same time. After the addition is completed, the mixture is kept warm for reaction for 2-3 hours.

[0014] (5) The material obtained in step (4) is supplemented with deionized water, cooled to 40° C., and potassium hydroxide is added for neutralization to obtain a polycarboxylic acid water reducer for machine-made sand concrete.

[0015] Preferably, the unsaturated anhydride is maleic anhydride, itaconic anhydride, nadic anhydride or (2,7-octadiene-1-yl) succinic anhydride; further preferably nadic anhydride or (2,7-octadiene-1-yl) succinic anhydride, more preferably (2,7-octadiene-1-yl) succinic anhydride. Experimental results show that when nadic anhydride or (2,7-octadiene-1-yl) succinic anhydride is used, the prepared water reducer can be applied to machine-made sand concrete, solving the problem of high segregation rate of machine-made sand concrete. The present invention attempts to prepare esterification monomers by molecular design using unsaturated anhydrides with different side chain lengths, and finds that the final water reducer prepared by nadic anhydride with a cyclic structure or long-chain (2,7-octadiene-1-yl) succinic anhydride can solve the problem of high segregation rate of machine-made sand concrete.

[0016] Preferably, calculated by weight, the ingredients include 80-100 parts of polypropylene glycol monobutyl ether, 20-25 parts of unsaturated acid anhydride, 1-2 parts of sulfuric acid, 0.2-0.3 parts of inhibitor, 80-90 parts of methyl allyl polyoxyethylene ether, 20-25 parts of methacrylic acid, 0.5-1.0 parts of reducing agent, 1-2 parts of chain transfer agent and 0.5-1.0 parts of initiator.

[0017] Preferably, the polypropylene glycol monobutyl ether has specifications of BPPG-350, BPPG-500, BPPG-750, and BPPG-1000; for example, it is selected from Jiangsu Haian Petrochemical, and more preferably BPPG-750.

[0018] Preferably, the methyl allyl polyoxyethylene ether is HPEG-2400

[0019] Preferably, the polymerization inhibitor is one of p-hydroxyanisole or phenothiazine.

[0020] Preferably, the reducing agent is sodium bisulfite or L-ascorbic acid;

[0021] Preferably, the chain transfer agent is at least one of thioglycolic acid, mercaptopropionic acid and sodium methacrylic acid.

[0022] Preferably, the initiator is at least one of ammonium persulfate, sodium persulfate and hydrogen peroxide.

[0023] This invention will be the first to realize the application of machine-made sand in high-performance concrete, which is of great significance to promoting the company to promote the application of machine-made sand concrete, environmentally friendly machine-made sand concrete and prefabricated building components. It has significant technical, economic and environmental benefits and will enhance the company's industry status.

[0024] Compared with the prior art, the present invention has the following significant advantages:

[0025] (1) The polycarboxylate water reducer prepared by the present invention can solve the problem of high segregation rate of machine-made sand concrete by using a special water reducer for machine-made sand concrete (the segregation rate of machine-made sand concrete prepared by the polycarboxylate water reducer of the present invention is less than 12%)

[0026] (2) The polycarboxylic acid water reducer of the present invention solves the problem of high segregation rate of machine-made sand concrete. By integrating the water reducer application technology and based on the molecular design and modification of the polycarboxylic acid water reducer, the polycarboxylic acid water reducer realizes the integrated functions of high water reduction, high slump retention and high thickening.

[0027] (3) The special water reducing agent for machine-made sand concrete of the present invention can achieve a segregation rate of machine-made sand concrete that meets the performance requirements of self-compacting concrete.

[0028] (4) The present invention can promote the advancement of the application technology of machine-made sand in concrete and the low-carbon development of concrete, and play a leading role in the concrete industry. DETAILED DESCRIPTION

[0029] Embodiment 1:

[0030] Prepare polycarboxylate water reducer for machine-made sand concrete according to the following steps:

[0031] (1) polypropylene glycol monobutyl ether (Hai'an Petrochemical, BPPG-750), unsaturated anhydride maleic anhydride, sulfuric acid and p-hydroxyanisole are mixed, heated to 170±2° C. for solvent-free reaction for 10-12 h to obtain an esterified monomer, cooled to room temperature and diluted with purified water to obtain a first mixed solution;

[0032] (2) adding methyl allyl polyoxyethylene ether HPEG-2400 to the first mixed solution, mixing, heating, and stirring to dissolve to obtain a second mixed solution;

[0033] (3) mixing methacrylic acid monomer with deionized water to obtain a monomer solution; mixing reducing agent sodium bisulfite, chain transfer agent thioglycolic acid and deionized water to obtain a functional additive solution;

[0034] (4) The second mixed solution is heated to 65-70°C, and the initiator ammonium persulfate is added. The mixture is kept warm for 15-30 minutes, and then the methacrylic acid monomer solution and the functional additive solution are added dropwise at the same time. After the addition is completed, the mixture is kept warm for 2-3 hours.

[0035] (5) The material obtained in step (4) is supplemented with deionized water, cooled to 40° C., and potassium hydroxide is added for neutralization to obtain a polycarboxylic acid water reducer for machine-made sand concrete.

[0036] Example 2

[0037] Compared with Example 1, an equal amount of itaconic anhydride was used to replace maleic anhydride, and the rest was the same.

[0038] Example 3

[0039] Compared with Example 1, an equal amount of nadic anhydride was used to replace maleic anhydride, and the rest was the same.

[0040] Example 4

[0041] Compared with Example 1, an equal amount of (2,7-octadien-1-yl)succinic anhydride was used to replace maleic anhydride, and the rest were the same.

[0042] The polycarboxylate water-reducing agent obtained in Examples 1-4 of the present invention was used in concrete (adjusted to a solid content of 15% during use, and the admixture amount was 1.5% of the gel material). The strength grade of the concrete in this test was C30, wherein the cement was 230 kg / m 3 , fly ash 50kg / m 3 , mineral powder 70kg / m 3 , machine-made sand 830kg / m 3 , small stone 300, large stone 710, water 170kg / m 3 The quality control of machine-made sand complies with the standard GB / T 14684-2011 "Construction Sand".

[0043] The initial state and the state after standing for 1 hour of fresh concrete prepared by the polycarboxylate water-reducing agent obtained in different embodiments were statistically analyzed, as shown in Table 1:

[0044] Table 1 Comparison of working conditions of fresh concrete

[0045]

[0046] Note: D1 is the concrete prepared by Point-TBS polycarboxylate high performance water reducing agent (standard type). VMA is

[0047] The experimental results show that for machine-made sand concrete, traditional polycarboxylate water reducers cannot solve the water bleeding performance of concrete. The present invention uses molecular design and the water reducers prepared by Examples 3 and 4 of the present invention to significantly improve the properties of machine-made sand concrete, improve the fluidity of the concrete, and after the concrete has been stationary for 1 hour, the concrete does not bleed, does not grab the bottom, has good wrapping and good fluidity. In particular, the water reducer in Example 4 can solve the water bleeding problem of machine-made sand concrete, and at the same time can achieve the integrated functions of high water reduction, high collapse retention, and high thickening.

[0048] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A polycarboxylate water reducer for machine-made sand concrete, prepared by the following method: (1) mixing polypropylene glycol monobutyl ether, unsaturated acid anhydride, sulfuric acid and a polymerization inhibitor, heating to carry out a solvent-free reaction to obtain an esterification monomer, cooling to room temperature and diluting with purified water to obtain a first mixed solution; (2) adding methyl allyl polyoxyethylene ether to the first mixed solution, mixing, heating, and stirring to dissolve to obtain a second mixed solution; (3) Mixing methacrylic acid monomer and deionized water to obtain a monomer solution; mixing a reducing agent, a chain transfer agent and deionized water to obtain a functional additive solution; (4) The second mixed solution is heated to 65-70°C, an initiator is added, and the mixture is kept warm for 15-30 minutes. Then, the methacrylic acid monomer solution and the functional additive solution are added dropwise at the same time. After the addition is completed, the mixture is kept warm for reaction for 2-3 hours. (5) The material obtained in step (4) is supplemented with deionized water, cooled to 40° C., and potassium hydroxide is added for neutralization to obtain a polycarboxylate water reducer for machine-made sand concrete; The unsaturated acid anhydride is nadic anhydride or (2,7-octadien-1-yl)succinic anhydride.

2. The polycarboxylate water reducer for machine-made sand concrete according to claim 1, characterized in that: The unsaturated acid anhydride is (2,7-octadien-1-yl)succinic anhydride.

3. The polycarboxylate water reducer for machine-made sand concrete according to any one of claims 1 to 2, characterized in that: Calculated by weight, the following ingredients include 80-100 parts of polypropylene glycol monobutyl ether, 20-25 parts of unsaturated acid anhydride, 1-2 parts of sulfuric acid, 0.2-0.3 parts of inhibitor, 80-90 parts of methyl allyl polyoxyethylene ether, 20-25 parts of methacrylic acid, 0.5-1.0 parts of reducing agent, 1-2 parts of chain transfer agent and 0.5-1.0 parts of initiator.

4. The polycarboxylate water reducer for machine-made sand concrete according to claim 1, characterized in that: The specifications of the polypropylene glycol monobutyl ether are BPPG-350, BPPG-500, BPPG-750, and BPPG-1000.

5. The polycarboxylate water reducer for machine-made sand concrete according to claim 1, characterized in that: The methyl allyl polyoxyethylene ether is HPEG-2400.

6. The polycarboxylate water reducer for machine-made sand concrete according to claim 1, characterized in that: The polymerization inhibitor is one of p-hydroxyanisole or phenothiazine.

7. The polycarboxylate water reducer for machine-made sand concrete according to claim 1, characterized in that: The reducing agents are sodium bisulfite and L-ascorbic acid.

8. The polycarboxylate water reducer for machine-made sand concrete according to claim 1, characterized in that: The chain transfer agent is at least one of thioglycolic acid, mercaptopropionic acid and sodium methacrylic acid, and the initiator is at least one of ammonium persulfate, sodium persulfate and hydrogen peroxide.

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